Protein and Amino Acid Needs
of the Strength Athlete
Peter W.R. Lemon
Kent State University
The debate regarding optimal proteinlamino acid needs of strength athletes
is an old one. Recent evidence indicates that actual requirements are higher
than those of more sedentary individuals, although this is not widely recognized. Some data even suggest that high proteinlamino acid diets can enhance
the development of muscle mass and strength when combined with heavy
resistance exercise training. Novices may have higher needs than experienced strength athletes, and substantial interindividual variability exists. Perhaps the most important single factor determining absolute proteinlamino
acid need is the adequacy of energy intake. Present data indicate that strength
athletes should consume approximately 12-15% of their daily total energy
intake as protein, or about 1.5-2.0 g proteinlkg*d-' (approximately 188250%of the U.S. recommended dietary allowance). Although routinely consumed by many strength athletes, higher protein intakes have not been shown
to be consistently effective and may even be associated with some health
risks.
Although for most of the 20th century nutritionists have generally believed
that proteinlamino acid need is not substantially affected by strength training
(87), many athletes, especially body builders, have routinely consumed very high
protein diets (41, 60). Apparently these individuals think such diets enhance
performance, but their opinion is based primarily on hearsay or uncontrolled
self-experimentation and therefore lacks the necessary objectivity to convince
scientists. However, recent results from several laboratories suggest that the
issue of whether such high proteinlamino acid diets are beneficial to strength
athletes rnay need to be readdressed (66). This paper reviews new information
relative to the previous literature and discusses the potential benefits of protein1
amino acid supplementation for the strength athlete.
Importance of Protein
Clearly, protein is an essential nutrient for all living organisms. With the exception of water, it is the largest component in our bodies and represents about 15%
of body weight. There are many proteins but each is made up of about 20 amino
Peter W.R. Lemon is with the Applied Physiology Research Laboratory, Kent State
University, Kent, OH 44242.
128 1 Lemon
acids; relative proportions of the amino acids distinguish individual proteins.
Although the process is somewhat complex, it is possible for the body to synthesize protein provided that all the amino acids are available (see Figure 1). Some
amino acids can be synthesized in the body from carbohydrate and/or fat carbon
and ammonia while others mstidine, isoleucine, leucine, lysine, methionine,
phenylalanine, threonine, tryptophan, valine), called indispensable or essential,
must be obtained through diet. If they are not, protein synthesis is impaired and,
over time, body protein content decreases. This means that the actual requirement
is for amino acids, not protein per se.
For this reason, recommendations have also been established for each of
the indispensable amino acids (87). As with protein, for which the current recommended dietary allowance (RDA) for adults is 0.8 glkg body weighted-' (87),
these recommendations are based primarily on the nitrogen balance technique of
nitrogen intake minus nitrogen excretion. Although these measures provide no
information about how protein metabolism is regulated, they are extremely valuable in assessing overall protein or individual amino acid needs.
Nitrogenous compounds in the body are constantly being degraded and
synthesized (Figure 1). Normally, when input of amino acids is adequate, both
processes are in balance and the body protein content remains stable. If intake is
inadequate, however, the rate of protein degradation can exceed synthesis and
result in an increased loss of tissue protein; nitrogen is excreted primarily in
urine but also in feces and sweat. This situation is called negative nitrogen balance because nitrogen excretion is greater than intake. Traditionally, two standard deviations in excess of the quantity of protein, or individual amino acid in
DIETARY PROTEIN
(AMINO ACIDS)
I
1
1
1
CHO/FATf
+ NH3
C OXIDIZED (C02)
/ FREE AMINO \ "
"
'1
I
ACID POOL I
BODY
-.
.-
' I '--U\u
I
l
l
nYIU
I
VVL
I
II
DEG
FECES
URINE
SWEAT
CHO or FAT
Figure 1 - Schematic representation of proteidamino acid metabolism. Amino
acids enter the body's free pools from the diet, from body protein, or via transarninated reactions with intermediary products of carbohydrate (CHO) or fat metabolism. Amino nitrogen leaves the free pools to form body protein or exits the body in
urine, sweat, and feces. Ammo carbon (C) leaves the free pools to form body fat/
CHO stores or exits the body as carbon dioxide (COJ. SYN = synthesis, DEG =
degradation.
Protein and Amino Acid Needs / 129
limiting amino acid studies, necessary to produce nitrogen balance in a study
group has been set as the RDA for the population (87). Although not an exact
determination of requirement, this recommendation should meet the needs of
approximately 95% of the population.
Recent information obtained from the use of metabolic tracer techniques
suggests that some amino acid needs may be 23-178% greater than estimated
using the balance technique (97). Resolution of this debate must await further
study but, regardless of that outcome, the tracer technique is a very important
addition to nitrogen balance methodology in assessing protein or amino acid
needs. This technique makes it possible to assess changes in the components of
protein turnover, that is, amino acids synthesized into protein, protein degraded
into amino acids, amino acids oxidized to CO,, and so forth.
Based primarily on nitrogen balance experiments, it is generally accepted
that several factors increase proteinlamino acid need: growth, energy deficit,
and lactation (87). In contrast, the effect of physical exercise on proteinlamino
acid need is considered minimal (87). However, this conclusion is based on
studies in which the subjects' exercise routines were minimal and therefore may
have little relevance to athletes in rigorous training.
A number of nitrogen balance experiments using athletes as subjects suggest that proteinlamino acid needs are greater in individuals who participate in
intense, intermittent exercise. For example, 20 years ago it was noted that a
protein intake of about 2 g/kg*d-' (250% RDA) was not enough to prevent a
negative nitrogen balance in at least 4 of 10 weightlifters (20). Similar studies
of Soviet weightlifters suggest that protein intakes of about 1.3-1.6 g/kg*d-'
(162-200% RDA) are necessary to avoid negative nitrogen balance (65). More
recent data (see Figure 2) indicate that protein requirements of experienced body
builders (>3 yrs training) may be closer to 0.9 g1kg.d-' (112%RDA) (83) while
those of novices during the first month of training are about 1.5 glkg-d-' (188 %
RDA) (68, 82). In addition, negative nitrogen balance data have also been reported with combined aerobiclanaerobictraining, as in 4 days of intern+ training
at 85-200% V02maxplus 1 day of 90-min continuous training at 65 % V02max/
week (43), or interval training 4.4 hrslday from 30 (warm-up) to 80% vo2max
followed immediately by a 90% V02max ride to exhaustion (12, 13, 14) even
though the subjects' intake exceeded the protein RDA.
Although it is not possible to determine which component(s) of protein
metabolism is (are) altered based on measures of nitrogen balance, these data
indicate that the current protein RDA is probably inadequate for athletes engaged
in this type of training. Further, it has long been known that if energy intake
is insufficient, protein needs are increased (75). With some athletes therefore,
especially those who restrict energy intake in an attempt to reduce body weight,
it is likely that daily protein needs may be even greater (90).
Potential Benefits of Increased Dietary
ProteinIAmino Acids for Strength Athletes
Possibility I
Surplus amino acids that become available during digestion of high protein diets
may provide additional raw material for enhanced protein synthesis and/or to
minimize protein breakdown. Given that heavy resistance training is a powerful
130 / Lemon
-
+18
-
.I6
-
GROUPS
BB LP
A
a
+lL -
BB HP
EA LP
-
E A HP
S LP
S HP
'
1
0
D
2
w
m
U
*12
z
-3
Q
.lo -
60
a8
3
a
0
0
m
0
(L
+--
-
-6
-
*4
-
z
.2 0'
-2
L
08
12
16
20
PROTEIN INTAKE
24
28
(g /kg.dayf
32
Figure 2 - Estimation of protein intake, based on low (LP) and high (HP) protein
diets, necessary to produce nitrogen balance in experiencedbody builders (BB), experienced endurance athletes @A), and sedentary controls (S) (83).
anabolic stimulus (84), this possibility has some merit. Many strength athletes
are absolutely convinced that this possibility exists. In contrast, most nutritionists
believe that excess dietary protein does not lead to greater muscle protein synthesis but instead results in increased nitrogen excretion, with the additional protein
carbon either oxidized or stored in the body in the form of carbohydrate and/or
fat.
Both of these viewpoints can be criticized. First, although the belief of the
strength athlete is based on much experimentationand is nearly universal, it must
be viewed with skepticism because the information on which it is based has been
gathered under conditions that were largely uncontrolled. Second, although it is
certainly true that nitrogen excretion increases with high protein diets, it may be
incorrect to assume that all excess nitrogen resulting from a high protein diet is
simply excreted. Unfortunately, most nitrogen balance studies have been conducted on sedentary individuals over relatively short periods of time.
However, at least one study (76) has demonstrated (Figure 3) that a highly
positive nitrogen balance can be maintained for at least 50 days when protein
Protein and Amino Acid Needs / 131
-,
@
,s
Y2
f
S
-
Figure 3
Nitrogen balance during prolonged (50 days) high protein intake. Day
of center refers to average of Sday measurements. Data of individual subjects are
shown (76).
intake is high (372 % RDA) . This being the case, it is perhaps possible that under
an anabolic stimulus such as heavy resistance exercise training, muscle protein
synthesis could be enhanced, resulting in increased muscle mass and strength. It
is even possible to find some experimental support for this from at least five
laboratories.
Consolazio et al. (21) found a greater nitrogen retention (32.4 vs. 7.1 g)
in men who trained (combined strength-endurance training) for 40 days when
protein intake was 2.8 (350% RDA) versus 1.4 g/kg*d-' (175% RDA). Moreover, the higher protein group experienced greater gains in lean body mass (3.28
vs. 1.21 kg), as measured by densitometry. Based on dietary nitrogen minus
urinary nitrogen, Marable et al. (72) calculated a greater nitrogen retention but
no differences in body weight gains in men who participated in a strength training
program while consuming 300 versus 100% of the protein RDA.
Over several months of strength training, Dragan et al. (24) observed 5%
gains in strength and 6% gains in lean body mass, based on skinfold measures,
when Romanian weightlifters increased their dietary protein from 275 to 438 %
of the RDA. Frontera et al. (35) reported that, over 12 weeks of strength training,
ingestion of a daily supplement containing 0.33 grams proteinlkg-d-' (33 kJ/
kg-d-') resulted in greater gains in thigh muscle mass (measured by computer-
132 / Lemon
ized axial tomography) and urinary creatinine (an index of whole body muscle
mass) when compared to training alone. We (68, 82) have also observed that a
high protein diet (334 vs. 124% RDA) produces greater nitrogen retention in
novice body builders during intensive training (6 daystwk, 3-day split routine, 4
x 8 repetitions to failure) (see Table 1). However, at least during the first month
of training this greater nitrogen retention was not readily apparent in measures
of muscle strength (1 RM) and mass (computerized axial tomography) (see Figure 4).
Alternatively, greater dietary proteinlamino acids may be advantageous
for the strength athlete in order to provide nitrogen to replace an accelerated
myofibrillar protein degradation caused by regular intense heavy resistance training. Although most studies of acute weightlifting exercise (51, 53) have failed
to detect increased excretion of 3-methylhistidine, a marker of myofibrillar
breakdown, (98), data are now accumulating which indicate that chronic strength
training results in an increased 3-methylhistidine excretion (36, 50, 77) (see
Figure 5).
Possibility 2
Amino acids that become available as a result of digestion may provide auxiliary
exercise fuel. Exercise has been shown to decrease protein synthesis and/or
increase protein breakdown (9). The resulting increased supply of amino acids
in the free pools (Figure 1) should lead to increased amino oxidation (1,47). In
fact it is well documented that, at least with endurance exercise, absolute oxidation of the amino acid leucine increases (4, 31,45, 67, 69, 78, 92). This effect
appears to be greatest at high exercise intensities (4, 69, 78, 92) and in trained
individuals (23, 49). Further, the magnitude of this response is substantial and
under prolonged endurance exercise conditions can approach daily requirements
Table 1
Nitrogen Balance of Novice Body Builders During First Month
of Intensive Training While Receiving Carbohydrate
or Protein Supplements
Supplement
N intake (gld)
N excretion (gld)
Urine
Feces
Sweat
N balance (gld)
Carbohydrate
Protein
12.8 f 0.9
34.8 f 1.3*
*
12.5
0.3
2.0 f 0.3
1.6 f 0.1
-3.4 f 0.5
Values are means f SE for 12 subjects per group.
'p<0.01 between supplements.
21.1
2.2
2.5
8.9
f
f
f
f
1.6'
0.3
0.1 *
1.2"
Protein and Amino Acid Needs 1 133
-
Figure 4
Computerized axial tomographic image of the arm from which crossand bone (b)mass can be estimated.
sectional areas of muscle (m), fat (0,
DAYS
Figure 5 - Repeated daily heavy resistance exercise and 3-methylhistidine excretion. E indicates beginning of the training program, * denotes increases (P<0.001)
relative to pretraining. Values are means SE (77).
*
134 / Lemon
(31). If other amino acids follow a similar pattern, dietary amino acid needs
could be substantially elevated by exercise.
Although these data are consistent with several nitrogen balance studies
involving high intensity exercise (34, 73, 83), they conflict with several others
that used lower intensity exercise (17, 40, 85) and found that protein requirements were actually reduced following adaptation to an exercise program. Few
individual amino acids have been studied to date (93), so it is not possible to
make a conclusion regarding exercise effects on overall amino acid need. However, this would appear to be a fruitful area for investigation because it is known
that muscle can oxidize at least six amino acids (39).
It is likely that the exercise-induced increased leucine oxidation is related
to the activation of branched-chain keto acid dehydrogenase (linuting enzyme in
the leucine oxidation pathway) by exercise intensity and/or duration (58,59, 89).
Further, the observed increases during endurance exercise are greater in humans
than in rodents (52), perhaps due to greater muscle dehydrogenase activity (61).
As a result of its very high intensity (70, 84), it is possible that strength
exercise also increases amino acid oxidation. However, our recent data (81) on
leucine oxidation during acute strength exercise (three sets of 10 repetitions for
each of nine exercises at 70% of 1 RM) indicate that this is not the case (see
Figure 6). Perhaps such exercise is so intense that its anaerobic nature minimizes
changes in amino acid oxidation. Therefore, if leucine is representative it would
appear that, unlike endurance exercise, amino acid oxidation does not play a
significant role in any increased protein/arnino acid need of strength athletes.
EXERCISE
-50
0
50
100
TIME (rnin)
150
200
Figure 6 - Whole-body leucine oxidation before, during, and following 60 minutes
of heavy resistance exercise (three sets of 10 repetitions for each of nine lifts at 70%
of 1 repetition max). A,B,C refers to method of grouping exercises. A = bench press,
sit-ups, leg press; B = lat pulldowns, biceps curls, knee extention; C = triceps press,
military press, leg press). Values are means f SE (81).
4
Protein and Amino Acid Needs / 135
**
Possibility 3
Amino acid ingestion may stimulate growth hormone release, resulting in increased muscle protein synthesis and muscle strength. This possibility involves
several issues. First, does increased growth hormone secretion result in enhanced
muscle strength and size? Second, does increased growth hormone release potentiate the anabolic effect of strength training? Third, does amino acid ingestion
increase growth hormone release? In order for Possibility 3 to play a significant
role for strength athletes, the answer to all three questions must be yes. Let's
examine each question.
Growth hormone is a powerful anabolic hormone that can have profound
effects on most body tissues either directly or through its effects on somatomedin
production in the liver (32). Its release from the pituitary gland is controlled by
the hypothalamus. Although both sexes experience pulsatile secretion throughout
the day, males have lower baseline values and more frequent and higher amplitude bursts than females (27). These pulses appear to be very important for
somatomedin (insulin-like growth factor) production (71) and growth (10, 18,
42). In addition, females are more sensitive to growth hormone stimulation, and
agedependent decreases occur in both males and females (64).
In growth hormone deficiency, administration of growth hormone will increase muscle mass and decrease fat mass in both humans and rodents (38, 57,
63,80). Growth hormone release involves a negative feedback system, however,
and the effects of exogenous growth hormone on normal muscle is less clear.
Early studies reported increased muscle cross-sectional area with growth hormone administrationto normal rodents but decreased tensionlg muscle (8). More
recent studies in rodents (25, 86) and humans (22) verify that an anabolic effect
is possible in normal muscle. Unfortunately, no measures of strength were reported in these studies. As a result, the data raise questions about the functional
importance of increased muscle mass induced by exogenous growth hormone
administration.
It is well known that heavy resistance training promotes muscle cell hypertrophy (see Figure 7) as a result of increased amino acid uptake and increased
net protein synthesis (3); however, the role of growth hormone is considered of
minor importance because training-induced hypertrophy occurs in hypophysectomized animals (37). Moreover, intense intermittent exercise stimulates growth
hormone release (88) (see Figure 8). What then is the role of increased growth
hormone in the process of exercise-induced hypertrophy?
Despite widespread reports that growth hormone administration to athletes
is commonplace, there is very little information on this topic. One study on
humans performing body building exercise found increased lean mass and decreased fat mass with growth hormone administration when compared to a placebo (22). In contrast, several other studies of exercise-induced hypertrophy in
both animals and humans have been unable to show a greater effect with growth
hormone administration. For example, Riss et al. (79) used surgical ablation to
induce hypertrophy in synergists and used growth hormone-producing pituitary
tumor cells to increase growth hormone in rodents, yet failed to produce greater
hypertrophy than the control group. We have been able to induce muscle hypertrophy in intact rodents (weight = 261 f19 g) by training them to climb (20
136 / Lemon
NORMALS
N=5
AND
POWERLIFTERS
Nz7
Figure 7 - Effect of heavy resistance exercise training (6 months for normals and
3-14 yrs for bodybuilderslpowerlifters) on muscle fiber cross-sectional area. FT =
fast twitch, ST = slow twitch (70).
5
J
0
3
----_
---Y
r
>
I
l
l
0
-10 - 3 0 4 7 10 1620 253035
I
60
T~me
(m~n)
-
Figure 8
Plasma growth hormone response to intense (0 = 7 sets of 7 vertical leg
presses at 85%of 7-repetitionmax) and moderate (a = 7 sets of 21 vertical leg presses
at 28% of 7-repetition max) heavy resistance exercise. T i e of exercise indicated by
hatched bar. Values are means f SE (88).
Protein and Amino Acid Needs / 137
climbslday, 5 dayslwk) a 90" incline with weight (406f 19 g) attached to their
tails (93, but we have not observed a greater response as a result of combined
training and growth hormone administration (unpublished data).
In a recent preliminary report of a study in which humans received growth
hormone injections (40 pglkg-d-l) while strength training (5 dayslwk at 75-90%
1 RM), lean mass gains (by densitometry) were greater relative to the placebo
group (4.0f 0.6 vs. 1.5 f0.3 kg) but no differences were observed in any measure of muscle strength or size (94). Therefore it would appear that although the
combination of training and growth hormone may enhance muscle development
relative to training alone, the data are inconsistent. Furthermore, there is no
published evidence that this practice leads to greater gains in strength.
The practice of consuming amino acid supplements, primarily arginineornithine or arginine-lysine, is based on the observation that intravenous administration of some amino acids causes an increased release of growth hormone (62)
(see Figure 9). The greatest responses are to methionine, arginine, phenylalanine, lysine, and histidine. Apparently elevated concentration of some plasma
amino acids can stimulate hypothalamic growth hormone releasing factors, perhaps mediated by insulin secretion, leading to an increased growth hormone
release. As a result, intravenous arginine infusion (30 g) is used widely as a
clinical test to evaluate hypothalamiclpituitary function; methionine is very toxic
(7). Intravenous infusion of omithine also stimulates growth hormone release, at
least in children (30); however, the mechanism of action is less clear. It could
also involve a direct effect on the hypothalamus or an indirect effect (increased
arginine) by inhibiting arginase activity (55).
Although often overlooked by the lay public, it is important to realize that
the growth hormone release effects of intravenous amino acid infusion may be
I
I
5
0-
I
Phenylalanlne A. . A
Histidine -0
Lysine A--A
. -@ Arginine
2
1
I
.
0 - - 0 Methlonine
0
Knopf et al. (1 965)
-10
-30
0
30
60
90
120
150
180
210
TIME (min)
-
Figure 9
Plasma growth hormone concentration before and after intravenous
administration (at time 0) of 30 g of select Gamino acids. Values are means f SE
(62).
lost with ingestion because of gastrointestinal involvement. Several studies (16,
56) have observed increased growth hormone release following ingestion of a
protein drink (20-60 g), and one study (54) reported large increases in growth
hormone and somatomedins following ingestion of small dosages of argininelysine (2.4 g) (see Figure 10). However, these effects were somewhat inconsistent and have been difficult to reproduce. Recently Bucci et al. (15) reported
small increases in growth hormone following ornithine ingestion, but only at
much higher dosages (170 mglkg or 12 gl70 kg).
In a series of experiments in our laboratory using dosages of arginineornithine (2: 1 ratio) up to 20 glday, we have observed only very modest effects
in <lo% of the subjects tested (unpublished data). Moreover, in these experiments the growth hormone release was smaller than observed with heavy resistance exercise and there was no evidence of an additive effect when the
supplementation was combined with heavy resistance training. Others who have
studied the combined effects of amino acid administration and exercise on growth
hormone release have found inconclusive results (5, 44, 74), but these studies
involved low intensity endurance exercise and therefore may not be relevant.
A few reports have appeared (6, 28, 29) which indicate substantial anabolic
effects of ingested amino acids with body building exercise. However, the results
of these studies are difficult to interpret due to lack of experimental control andlor
questionable design. In short, very few data support the idea that oral amino acid
supplementationwill enhance muscle development through growth hormone release.
CostlBenefit Ratio of High Dietary Protein or Amino Acids
In general, high protein diets are discouraged by most nutritionists for several
reasons: (a) Protein increases the work of the kidney, due to the associated high
nitrogen load, and increases concern for the dehydrating effects of exercise, due
-
-a
Arglnlne
+ Lyslns (1.2g + 1.29)
- 0 Argtnine (1.2g)
A -A Arglnlne (2.49)
0-
0 .. .
* SD
Lyslne (l.Zg)
a
lsidori et al. (1 981)
.......
TIME (rnin)
Figure 10 - Plasma growth hormone response to oral administration (at time 0) of
arginine-lysine. Values are means f SD (54).
Protein and Amino Acid Needs 1 139
to the associated greater urinary water loss; (b) some protein diets are associated
with high fat intake and this can lead to accelerated atherogenesis (19); and
(c) high protein diets may increase calcium loss (2).
Although each of these has some basis in fact, it may be that the concern
is somewhat overstated. For example, the observed calcium loss with purified
proteins may be prevented with the increased phosphate intake that would occur
with most food protein (33). Dehydration can be avoided by consuming several
extra glasses of water a day and by monitoring changes in body weight. Clearly,
high fat intakes should be avoided but the association between animal protein
and plasma cholesterol observed in animal studies may not apply to humans (91).
The suggestion that high protein diets contribute to the progressive nature of
kidney disease comes from data on kidney patients (11). There is no published
evidence that strength athletes have an increased incidence of renal disease. Further, studies in rodents have demonstrated that extremely high protein diets (80%
of total energy intake) for over 50 % of their life span produced minimal negative
effects (99). Finally, several human populations whose protein intake is traditionally high (250-300 glday) seem to avoid these problems (26).
In contrast, more caution is advised with respect to the intake of large
dosages of individual amino acids because the costlbenefit of this practice remains largely untested. It is known that large intakes of some single amino acids
can interfere with absorption and lead to metabolic imbalances (48). Bucci et
al. (15) observed xnild to severe stomach cramping and diarrhea with ornithine
ingestion. Other amino acids can alter brain neurotransmitter activity (96) and
some are very toxic (7,46,48).
Summary and Conclusions
Although the cunent recommended dietary allowance does not recognize that
proteinlamino acid needs are higher in strength athletes, there is a substantial
amount of experimental support to the contrary. Unfortunately, it is not yet
possible to determine precise dietary proteinlamino acid recommendations.
However, it may be that requirements are greater for novices than for more
experienced strength athletes, and there is likely to be significant individual
variabilitv.
O& of the most important factors affecting the absoluteproteinlamino acid
needs of strength athletes is energy intake. If high proteinlamino acid diets are
advantageous, it may be due to increased muscle protein synthesis caused by the
interaction of increased amino acid availability and the enhanced anabolic stimulus of heavy resistance exercise. Measurement of nitrogen balance is not sufficient to determine whether proteinlamino acid intake is adequate. Future studies
employing direct measures of changes in muscle mass and strength are needed
before the optimum proteinfamino acid intake can be determined.
Based on available data, it would appear that a diet that provides approximately 1.5-2.0 g protein/kg*d-' should be adequate for strength athletes, assuming overall energy needs are met. This amount of protein can be obtained by
consuming a mixed diet containing 12-15 % of its energy from protein. Although
the epidemiological evidence is not yet available on strength athletes, it may be
prudent to avoid proteinJamino acid intakes higher than this, not only because
they have not been shown to consistently enhance muscle strength or size gains
but also because of potential negative health effects including accelerated atherogenesis and kidney disease.
140 / Lemon
1. Aftring, R.P., W.J. Miller, and M.G. Buse. Effects of diabetes and starvation on
slceletal m s c l e branch&-chaia alpha-keto a d d dehydrogenase activity. dm. J. Playsiol. 254.33292-E300, 3.988.
2. Allen, E.B., E. A. Oddoye, and S. Margen. Protein-induced hypercalciuria: A longer
a m study. Am. J. CEin. Num. 32:741-749, 1979.
3. Augerh, G., S. Monier, and Y. LeMarcRand-Bmstd. Effect s f exercise on protein
turnover in musdes of lean and obese mi=. Ddabetologira 29:248-253, 1986.
4. Babij, P., S.M. Matthews, and M.J. Rennie. Changes in blood ammonia, lactate and
amino acids in relation to worldoad during bicycle ergometer exercise in man. Eur.
J. Appl. &>hyskol. 50:405411, 1983.
5. Barr, S.I., C.J. Enns, and J.Q. Macintyre. Rack of effect of suppBementa8 arginine
and ornithhe in exercising rats. (Abstract) Med Sci. &m-ts B e r . 19 (2, suppl.):
S68, 1987.
6. Beckett, K.D., and R. Slagle. Amino acids: A controlled experiment. Muscle Fit.
pp. 76-77, September 1986.
7. Benevenga, I\J.J., and R.D. Steele. Adverse effects of excessive consumption of
amino acids. Ann. Rev. Nutr. 4:15'3-181, 1984.
8. Bigland, B., m d B. Jehring. Muscle performance in rats, normal and treated with
growth hormone. J. Physiol. B 16: 129-136, 1952.
9. Booth, P.W., and P.A. Watson. Control of adaptations in protein levels in response
to exercise. Fed. Proc. 44:2293-2300, 1985.
10. Borer, K.T., D.R. Nicoski, and V. Owens. Alteration of pulsatile growth hormone
secretion by growth-inducing exercise: Tnvolvement of endogenous opiates and somatostatin. Endocrinol. 118: 844-850, 1986.
11. Brenner, B.M., T.W. Meyer, and T.H. Hostetter. Dietary protein intake and the
progressive nature of kidney disease: The role of hernodynamically mediated glomerular injury in the pathogenesis of progressive g l o m e d a r sclerosis in aging, renal
ablation and intrinsic renal disease. N. EngE. J. Med 307552-659, 8982.
12. Brouns, F., W.H.M. Saris, J. Stroecken, E. Beckers, W. Thussen, N.9. Rehrer, and
P. ten Moor. Eating, drinking, and cycling. A controlEed Tour de Prance simulation
study, Part I. Int. J. Sports Med. 10 (suppl. B):S32-S40, 1989.
13. Brouns, F., W.W.M. Saris, J. Stroecken, E. Beckers, R. Thijssen, N.J. Rehrer, and
F. ten Nmr. Eating, drinking, and cycling. A controlled T w r de Prance simulation
study, Part TI. Bnt. J. Sports Med. I0 (suppl. 1):S41-S48, 1989.
14. Brouns, F., W.B.M. Saris, E. Beckers, H. Adlercreutz, G.J. v m der Vusse, W.A.
Keker, H. Kuipers, P. Menheere, A.J.M. Wagenmakers, and F. ten Moor. Metabolic changes induced by sustained exhaustive cycling and diet manipulation. Int. J.
Sports Med. 10 (Suppl B):S49-S62, 1989.
15. Bucci, L.,J.F. Hickson, J.M. Pivarnik, 1. Wolinsky, J.C. McMahon, and S.D.
Turner. O w i t h e ingestion and growth hormone release in bodybuilders. Nutr. Res.
10:239-245, 1990.
16. Buckler, 9.M. The effect of age, sex, and exercise on the secretion of growth hormone. Qin. Sci. 37:765-774, 1969.
17. Butterfield, G.B., and D.H. Cdloway. .Physical activity improves protein utilization
in young men. Br. J. Nutr. 51: 171-184, 1984.
18. Cameron, C.M., J.E. k s t y o , N.A. Adamafio, . Brostedt, P. Roos, A. Skottner,
A. Forsmn, L. Fryldmd, and B. Skoog. The acute effects of growth hormone on
Protein and Amino Acid Needs / 141
amino acid transport and protein synthesis are due to its insulin-like action. Endoc&nol. 122:471-474, 1988.
19. Carroll, K.K. Hypercholesterolemiaand atherosclerosis: Effects of dietary protein.
Fed. Proc. 41:2792-2796,1982.
20. Celejowa, I., and M. Horna. Food intake, nitrogen, and energy balance in Polish
weight lifters during a training camp. Nutr. Metabol. 12:259-274, 1970.
21. Consolazio, C.F., R.A. Nelson, L.O. Matoush, R.S. Harding, and J.E. Canham.
Nitrogen excretion in sweat and its relation to nitrogen balance experiments. J. Nutr.
79:399-406, 1963.
22. Crist, D.M., G.T. Peake, P.A. Egan, and D.L. Waters. Body composition response
to exogenous GH during training in highly conditioned adults. J. Appl. Physiol.
65:579-584, 1988.
23. Dohm, G.L., A.L. Hecker, W.E. Brown, G.J. Klain, F.R. Puente, E.W. Askew,
and G.R. Beecher. Adaptation of protein metabolism to endurancetraining. Increased
amino acid oxidation in response to training. Biochem. J. 164:705-708, 1977.
24. Dragan, G.I., A. Vasiliu, and E. Georgescu. Effects of increased supply of protein
on elite weight lifters. In Milk Proteins '84, T.E. Galesloot and B.J. Tinbergen
(Eds.), Wageningen, The Netherlands: Pudoc, 1985, pp. 99-103.
25. Dudley, G.A., and R. Portanova. Histochemical characteristics of soleus muscle in
hGH transgenic mice. Proc. Soc. Q. Biol. Med. 185:403-408, 1987.
26. Durnin, J.V.G.A. Protein requirements and physical activity. In Nutrition, Physical
Fitness, and Health, J. Parizkova and V.A. Rogozkin (Eds.), Baltimore: University
Park Press, 1978, pp. 53-60.
27. Eden, S. Age- and sex-related differences in episodic growth hormone secretion in
the rat. Endocrinol. 105:555-560,1979.
28. Elam, R.P. Morphological changes in adult males from resistance exercise and amino
acid supplementation. J. Spt. Med. Phy. Fit. 28:35-39, 1988.
29. Elarn, R.P., D.H. Hardin, R.A.L. Sutton, and L. Hagen. Effects of arginine and
ornithine on strength, lean body mass and urinary hydroxyproline in adult males. J.
Spt. Med. Phy. Fit. 2952-56, 1989.
30. Evain-Brion, D., M. Donnadieu, M. Roger, and J.C. Job. Simultaneous study of
somatotrophic and corticotrophic pituitary secretions during ornithine infusion test.
Clin. Endocrinol. 17:119-122, 1982.
31. Evans, W.J., E.C. Fisher, R.A. Hoerr, and V.R. Young. Protein metabolism and
endurance exercise. Phys. Sportsmed. 11:63-72,1983.
32. Florini, J.R. Hormonal control of muscle growth. Muscle Nerve 10:577-598, 1987.
33. Flynn, A. Milk proteins in the diets of those of intermediate years. In Milk Proteins
'84, T.E. Galesloot and B.J. Tinbergen (Eds.), Wageningen, The Netherlands:
Pudoc, 1985, pp. 154-159.
34. Friedman, J.E., and P.W.R. Lemon. Effect of chronic endurance exercise on retention of dietary protein. Znt. J. Sports Med. 10:118-123, 1989.
35. Frontera, W.R., C.N. Meredith, and W.J. Evans. Dietary effects on muscle strength
gain and hypertrophy during heavy resistance training in older men. (Abstract) Can.
J. Sport Sci. 13(2):13P, 1988.
36. Frontera, W.R., C.N. Meredith, K.P. O'Reilly, H.G. Knuttgen, and W.J. Evans.
Strength conditioning in older men: Skeletal muscle hypertrophy and improved function. J. Appl. Physiol. 64:1038-1044, 1988.
37. Goldberg, A.L. Work-induced growth of skeletal muscle in normal and hypophysectomized rats. Am. J. Physiol. 213:1193-1198, 1967.
142 1 Lemon
38. Goldberg, A.L., and H.M. Goodman. Relationship between growth hormone and
muscular work in determining muscle size. J. Physiol. 200:655-666, 1969.
39. Goldberg, A.L., and R. Odessey. Oxidation of amino acids by diaphragms from fed
and fasted rats. Am. J. Physiol. 223: 1284-1391, 1972.
40. Gontzea, I., P. Sutzescu, and S. Dumitrache. The influence of adaptation to physical
effort on nitrogen balance in man. Nutr. Rep. Znt. 11:231-234, 1975.
41. Grandjean, A.C. Current nutrition beliefs and practices in athletes for weight1
strength gains. In Muscle Development: Nutritional Alternatives to Anabolic Steroids,
W.E. Garrett, Jr. and T.R. Malone (Eds.), Columbus, OH: Ross Laboratories, 1988,
pp. 56-61.
42. Groesbeck, M.D., A.F. Parlow, and W.H. Daughaday. Stimulation of supranormal
growth in prepubertal, adult plateaued, and hypophysectomized female rats by large
doses of rat growth hormone: Physiological effects and adverse consequences. Endocrinol. 120:1963-1975, 1987.
43. Hackney, A.C., R.L. Sharp, W. Runyan, Y. Kim, and R.J. Ness. The effects of
combined aerobic-anaerobic training on post exercise nitrogen excretion. (Abstract)
Can. J. Sport Sci. 13(2):14P, 1988.
44. Hagen, T.C., A.M. Lawrence, and L. Kirsteins. Autoregulation of growth hormone
secretion in normal subjects. Metabolism 21:603-610, 1972.
45. Hagg, S.A., E.L. Morse, and S.A. Adibi. Effect of exercise on rates of oxidation,
turnover, and clearance of leucine in human subjects. Am. J. Physiol. 242:E407E410, 1982.
46. Hargrove, D.M., Q.R. Rogers, C.C. Calvert, and J.G. Moms. Effects of dietary
excesses of branched-chain amino acids on growth, food intake and plasma amino
acid concentrations in kittens. J. Nutr. 118:311-320, 1988.
47. Harper, A.E. Control mechanisms in amino acid metabolism. In Control of Metabolism, J.D. Sink (Ed.), University Park, PA: Pennsylvania State University Press,
1974, pp. 49-74.
48. Harper, A.E., N.J. Benevenga, and R.M. Wohlheuter. Effects of ingestion of disproportionate amounts of amino acids. Physiol. Rev. 50:428-557, 1970.
49. Henderson, S.A., A.L. Black, and G.A. Brooks. Leucine turnover and oxidation in
trained rats during exercise. Am. J. Physiol. 249:E137-E144, 1985.
50. Hickson, J.F., and K. Hinkelmann. Exercise and protein intake effects on urinary 3methylhistidine excretion. Am. J. Clin. Nutr. 41:246-253, 1985.
51. Hickson, J.F., I. Wolinsky, G.P. Rodriguez, J.M. Pivernik, M.C. Kent, and N.W.
Shier. Failure of weight training to affect urinary indices of protein metabolism in
men. Med. Sci. Sports Exer. 18563-567, 1986.
52. Hood, D.A., and R.L. Terjung. Amino acid metabolism during exercise and following endurance training. Sports Med. 9~23-35,1990.
53. Horswill, C.A., D.K. Layman, R.A. Boileau, B.T. Williams, and B.H. Massey.
Excretion of 3-methylhistidine and hydroxyproline following acute weight-training
exercise. Znt. J. Sports Med. 9:245-248, 1988.
54. Isidori, A., A. Lo Monaco, and M. Cappa. A study of growth hormone release in
man after oral administration of amino acids. Curr. Med. Res. Opin. 7:475-481,
1981.
55. Iwasaki, K., K. Mano, M. Ishihara, Y. Yugari, and T. Matsuzawa. Effects of ornithine or arginine administration on serum amino acid levels. Biochem. Internat.
14:971-976, 1987.
56. Jackson, D., D.B. Grant, and B. Clayton. A simple oral test of growth hormone
secretion in children. Lancet 2:373-375, 1968.
Protein and Amino Acid Needs / 143
57. Jorgensen, J.O.L., L. Thuesen, T. Ingemann-Hansen, S.A. Pedersen, J. Jorgensen,
N.E. Skakkebaek, and J.S. Christiansen. Beneficial effects of growth hormone treatment in GH-deficient adults. Lancet 1:1221-1225, 1989.
58. Kasperek, G.J., G.L. Dohrn, and R.D. Snider. Activation of branched-chain keto
acid dehydrogenase by exercise. Am. J. Physiol. 248:E166-E177, 1985.
59. Kasperek, G.J., and R.D. Snider. Effect of exercise intensity and starvation on activation of branched-chain keto acid dehydrogenase by exercise. Am. J. Physiol.
252:E33-E37,1987.
60. Katch, V.L., F.I. Katch, R. Moffatt, and M. Gittleson. Muscular development and
lean body mass in body builders and weight lifters. Med. Sci. Sports Exer. 12:340344,1980.
61. Khatra, B.S., R.K. Chawla, C.W. Sewell, and D. Rudman. Distributionofbranchedchain alpha-keta acid dehydrogeneses in primate tissues. J. Clin. Invest. 59558-564,
1977.
62. Knopf, R.F., J.W. Conn, S.S. Fajans, J.C. Floyd, E.M. Guntsche, and J.A. Rull.
Plasma growth hormone response to intravenous administration of amino acids. J.
Clin. Endocrinol. Metab. 25: 1140-1144, 1965.
63. Kostyo, J.L., and D.F. Nutting. Acute in vivo action of growth hormone on various
tissue of hypophysectomized rats and their relationship to the levels of thymidine
factor and insulin in the plasma. Horm. Metab. Res. 5: 167-171, 1973.
64. Lang, I., G. Schernthaner, P. Pietschmann, R. Kurz, J.M. Stephenson, and H.
Templ. Effects of sex and age on growth hormone response to growth hormonereleasing hormone in healthy individuals. J. Clin. Endocrinol. Metab. 65:535-540,
1987.
65. Laritcheva, K.A., N.I. Yalovaya, V.I. Shabin, and P.V. Smimow. Study of energy
expenditure and protein needs of top weight lifters. In Nutrition, Physical Fitness,
and Health, J. Parizkova and V.A. Rogozkin (Eds.), Baltimore: University Park
Press, 1978, pp. 155-163.
66. Lemon, P.W.R. Nutrition for muscular development of young athletes. In Perspectives in Exercise Science and Sports Medicine, Vol. 10, Youth, Exercise, and Sport,
C.V. Gisolfi and D.R. Lamb (Eds.), Indianapolis: Benchmark Press, 1989, pp. 369400.
67. Lemon, P. W.R., N.J. Benevenga, J.P. Mullin, and F.J. Nagle. Effect of daily exercise and food intake on leucine oxidation. Biochem. Med. 33:67-76, 1985.
68. Lemon, P.W.R., J.D. MacDougall, M.A. Tarnopolsky, and S.A. Atkinson. Effect
of dietary protein and body building exercise on muscle mass and strength gains.
(Abstract) Can. J. Sport Sci. 15(4):14!5, 1990.
69. Lemon, P.W.R., F.J. Nagle, J.P. Mullin, and N.J. Benevenga. In vivo leucine
oxidation at rest and during two intensities of exercise. J. Appl. Physiol. 53:947-954,
1982.
70. MacDougall, J.D., D.G. Sale, G.C.B. Elder, and J.R. Sutton. Muscle ultrastructural
characteristicsof elite powerlifters and bodybuilders. Eur. J. Appl. Physiol. 48:117126,1982.
71. Maiter, D., L.E. Underwood, M. Maes, M.L. Davenport, and J.M. Ketelslegers.
Different effects of intermittent and continuous growth hormone (GH) administration
on serum somatomedin-Ctinsulin-likegrowth factor I and liver GH receptors in hypophysectomized rats. Endocrinol. 123:1053-1059, 1988.
72. Marable, N.J., J.R. Hickson, M.K. Korslund, W.G. Herbert, R.F. Desjardins, and
F.W. Thye. Urinary nitrogen excretion as influenced by a muscle-building exercise
program and protein intake variation. Nutr. Rep. Znt. 19:795-805, 1979.
144 1 Lemon
73. Meredith, C.M., M.J. Zackin, W.J. Frontera, and W.J. Evans. Dietary protein
requirements and body protein metabolism in endurance-trained men. J. Appl. Physiol. 66:2850-2856, 1989.
74. Merimee, T.J., D. Rabinowitz, and S.E. Fineberg. Arginine-initiated release of
human growth hormone. N. Engl. J. Med. 280:1434-1438, 1969.
75. Munro, H.N. Carbohydrate and fat as factors in protein utilization and metabolism.
Physiol. Rev. 31:449-488, 1951.
76. Oddoye, E.B., and S. Margen. Nitrogen balance studies in humans: Long term effect
of high nitrogen intake on accretion. J. Nutr. 109:363-377, 1979.
77. Pivarnik, J.M., J.F. Hickson, and I. Wolinsky . Urinary 3-methylhistidine excretion
increases with repeated weight training exercise. Med. Sci. Sports Exer. 21:283-287,
1989.
78. Rennie, M.J., R.H.T. Edwards, S. Krywawych, C.T.M. Davies, D. Halliday, and
D.J. Milliward. Effect of exercise on protein turnover in man. Clin. Sci. 61:627639, 1981.
79. Riss, T.L., J. Novakofski, and P.J. Bechtel. Skeletal muscle hypertrophy in rats
having growth hormone-secreting tumor. J. Appl. Physiol. 61 :1732-1735, 1986.
80. Salomon, F., R.C. Cuneo, R. Hesp, and P.H. Sonksen. The effects of treatment with
recombinant human growth hormone on body composition and metabolism in adults
with growth hormone deficiency. N. Engl. J. Med. 321: 1797-1803, 1989.
8 1. Tarnopolsky, M.A., S.A. Atkinson, J.D. MacDougall, B.B. Senor, P.W.R. Lemon,
and H. Schwarcz. Whole body leucine metabolism during and after resistance exercise in fed humans. Med. Sci. Sports Exer. 23 :326-333, 1991.
82. Tarnopolsky, M.A., P.W.R. Lemon, J.D. MacDougall, and S.A. Atkinson. Effect
of body building exercise on protein requirements. (Abstract) Can. J. Sport Sci.
15(4):22S, 1990.
83. Tarnopolsky, M.A., J.D. MacDougall, and S.A. Atkinson. Influence of protein intake and training status on nitrogen balance and lean body mass. J. Appl. Physiol.
64:187-193, 1988.
84. Tesch, P.A. Acute and long-term metabolic changes consequent to heavy-resistance
exercise. In Medicine and Sport Science, Vol. 26, M. Hebbelinck and R.J. Shephard
(Eds.), Basel, Switzerland: Karger, 1987, pp. 67-89.
85. Todd, K.S., G.E. Butterfield, and D.H. Calloway. Nitrogen balance in men with
adequate and deficient energy intake at three levels of work. J. Nutr. 114:2107-2118,
1984.
86. Ullman, M., H. Alameddine, A. Skottner, and A. Oldfors. Effect of growth hormone
on skeletal muscle. 11. Studies on regeneration and denervation in adult rats. Acta
Physiol. Scand. 135537-544, 1989.
87. U.S. Food and Nutrition Board. Recommended Dietary Allowances, Vol. 10, Washington, DC: National Academy Press, 1989, pp. 52-77.
88. Vanhelder, W.P., M.W. Radomski, and R.C. Goode. Growth hormone responses
during intermittent weight lifting exercise in men. Eur. J. Appl. Physiol. 53:31-34,
1984.
89. Wagenmakers, A.J.M., J.H. Coakley, and R.H.T. Edwards. Metabolism of
branched-chain amino acids and ammonia during exercise: Clues from McArdle's
disease. Znt. J. Sports Med. 11 (suppl. 2):SlOl-S 113, 1990.
90. Walberg, J.L., M.K. Leidy, D.J. Sturgill, D.E. Hinkle, S.J. Ritchey, and D.R.
Sebolt. Macronutrient content of a hypoenergy diet affects nitrogen retention and
muscle function in weight lifters. Znt. J. Sports Med. 9:261-266, 1988.
Protein and Amino Acid Needs / 145
91. West, C.E., and A.C. Beynen. Milk proteins in contrast to plant proteins: Effects on
plasma cholesterol. In Milk Proteins '84, T.E. Galesloot and B.J. Tinbergen (Eds.),
Wageningen, The Netherlands: Pudoc, 1985, pp. 80-87.
92. White, T.P., and G.A. Brooks. [u-14C] glucose, -alanine, -1eucine oxidation in rats
at rest and during two intensities of running. Am. J. Physiol. 240:E155-E165, 1981.
93. Wolfe, R.R., M.H. Wolfe, E.R. Nadel, and J.H.F. Shaw. Isotopic determination of
amino acid-urea interactions in exercise in humans. J. Appl. Physiol. 56:221-229,
1984.
94. Yarasheski, K.E., J.A. Campbell, M.J. Rennie, J.O. Holloszy, and D.M. Bier.
Effect of strength training and growth hormone administration on whole body and
skeletal muscle leucine metabolism. (Abstract) Med. Sci. Sports Exer. 22 (2, suppl.):
S85, 1990.
95. Yarasheski, K.E., P.W.R. Lemon, and J. Gilloteaux. Effect of heavy-resistance
exercise training on muscle fiber composition in young rats. J. Appl. Physiol. 69:434437,1990.
96. Yokogoshi, H., T. Iwata, K. Ishida, and A. Yoshida. Effect of amino acid supplementation to low protein diet on brain and plasma levels of tryptophan and brain 5hydroxyindoles in rats. J. Nutr. 117:42-47, 1987.
97. Young, V.R., D.M. Bier, and P.L. Pellet. A theoretical basis for increasing current
estimates for the amino acid requirements in adult man with experimental support.
Am. J. Clin. Nutr. 50:80-92, 1989.
98. Young, V.R., and H.N. Munro. N+-methylhistidine (3-methylhistidine) and muscle
protein turnover: An overview. Fed. Proc. 37:2291-2300, 1978.
99. Zaragoza, R., J. Renau-Piqueras, M. Portoles, J. Hemandex-Yago, A. Jorda, and
S. Grisolia. Rats fed prolonged high protein diets show an increase in nitrogen metabolism and liver megamitochondria. Arch. Biochem. Biophys. 258:426-435, 1987.
Acknowledgment
Sincere appreciation is expressed to Ms. Jan Wilmoth for her expert secretarial
assistance.